* {
  box-sizing: border-box;
}
h1 {
  color: red;
}
h2 {
  color: green;
}
h3 {
  color: blue;
}
p {
  font-size: 25px;
  color: teal;
}
.flex-center {
  display: flex;
  justify-content: center;
  align-items: center;
}